<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    .title{
      width: 100%;
      height: 50px;
      background-color: black;
      position: relative;
    }
    .logo{
      width: 100px;
      height: 50px;
      float: left;
      color: white;
      position: absolute;
      left: 200px;
      line-height: 50px;
    }
    .nav{
        width: 400px;
        height: 50px;
        float: left;
        color: white;
        position: absolute;
        right: 10px;
        line-height: 50px;
    }
    .nav div{
        margin-left: 10px;
        display: inline-block;
    }
    .nav div:hover{
        background-color: skyblue;
    }
    .div1{
        width: 150px;
        height: 50px;
        float: left;
        background-color: black;
        position: absolute;
        top: 50px;
        left: 10px;
        display: none!important;
        text-align: center;
        line-height: 50px;
        color: white;
    }
    .div2{
            width: 150px;
            height: 50px;
            /*float: left;*/
            background-color: black;
            position: absolute;
            top: 50px;
            left: 50%;
        transform: translateX(-50%);
            display: none!important;
            text-align: center;
            line-height: 50px;
            color: white;
    }
    .div3{
        width: 150px;
        height: 50px;
        float: left;
        background-color: black;
        position: absolute;
        top: 50px;
        left: 48px;
        display: none!important;
        text-align: center;
        line-height: 50px;
        color: white;
    }
    .div4{
        width: 150px;
        height: 50px;
        float: left;
        background-color: black;
        position: absolute;
        top: 50px;
        left: 32px;
        display: none!important;
        text-align: center;
        line-height: 62px;
        color: white;
    }
    .div11:hover .div1 {
        display: block!important; /* 鼠标悬停时显示 */
    }
    .div22:hover .div2 {
        display: block!important; /* 鼠标悬停时显示 */
    }
    .div33:hover .div3 {
        display: block!important; /* 鼠标悬停时显示 */
    }
    .div44:hover .div4 {
        display: block!important; /* 鼠标悬停时显示 */
    }
  </style>
</head>
<body>
<div class="title">
<div class="logo">网站logo</div>
  <div class="nav">
      <div>首页</div>
      <div class="div11">产品<div class="div1">查看我们的产品</div></div>
      <div class="div22">服务<div class="div2">查看我们的服务</div></div>
      <div class="div33">关于<div class="div3">关于我们</div></div>
      <div class="div44">联系<div class="div4">联系我们</div></div>
  </div>
</div>
<h1 style="position: absolute;left: 50%;transform:translateX(-50%)">向下滚动查看"返回顶部"按钮</h1>
</body>
</html>